Characterization of novel inhibitors of HIV-1 replication that function via alteration of viral RNA processing and rev function

Abstract

Expression of the complete HIV-1 genome depends on the appropriate processing of viral RNA. Altering the balance of viral RNA processing impairs replication of the virus. In this report, we characterize two small molecule modulators of HIV-1 RNA processing, 8-azaguanine and 2-(2-(5-nitro-2-thienyl)vinyl)quinoline (5350150), which function by distinct mechanisms to suppress viral gene expression. Although only 8-Azaguanine dramatically decreased accumulation of HIV-1 unspliced and singly spliced RNAs and altered splice site usage, both compounds blocked Gag and Env expression without affecting production of Tat (p16) and Rev regulatory proteins. Subsequent analyses suggest that these compounds affect Rev-mediated RNA transport by different mechanisms. Both compounds induced cytoplasmic accumulation of Rev, suggesting that they function, in part, by impairing Rev function. This conclusion is supported by the determination that both drugs block the nuclear export of genomic HIV-1 RNA to the cytoplasm. Testing confirmed that these compounds suppress HIV-1 expression in T cells at doses below those previously used in humans for tumour chemotherapy. Together, our observations demonstrate that small molecules can be used to inhibit HIV-1 replication by altering another avenue of viral RNA processing, offering the potential for the development of novel therapeutics for controlling this disease.

RRE-dependent HIV-1 Env RNA effects on Gag protein expression, assembly and release

“…Nevertheless, it remains possible that variations in nuclear exit strategies, or effects on host factors impacting stabilities, modifications, or trafficking may influence the fates of messages and their translation products (Swanson et al, 2004; Cullen, 2005; Sherer et al, 2009; Jin et al, 2009). In either case, our data strongly support the idea that inhibition of HIV-1 vRNA nuclear export is a potentially viable anti-viral approach (Mautino and Morgan, 2002; Ward et al, 2009; Wong et al, 2013). …”

An activator of G protein-coupled receptor and MEK1/2-ERK1/2 signaling inhibits HIV-1 replication by altering viral RNA processing

“…As a test of this approach, we examined small molecule modulators of SMN2 RNA AS and identified 5342191 as an inhibitor of HIV-1 replication. While targeting components of the core splicing apparatus (requiring coordinated functioning of many host proteins for removal of introns from RNAs) may be toxic [65], modulation of factors regulating splice site use, such as SR proteins or heterogeneous nuclear ribonucleoproteins, may not have as severe of an effect on the host [27,39,41,42,66]. Our characterization of 5342191 as a potent inhibitor of HIV-1 replication (Fig 1) validates this hypothesis.…”

“…Rev is critical in mediating nuclear export of incompletely-spliced (US/SS) HIV-1 RNAs to the cytoplasm while Tat is essential as a transactivator of viral transcription [35][36][37][38]. These results (and data on HIV-1 RNAs and SR proteins described below) are in mark contrast to previous HIV-1 RNA-processing inhibitors reported, suggesting a novel mechanism of action [27,28,33,[39][40][41][42][43].…”

A Cell-penetrating Antibody Fragment against HIV-1 Rev Has High Antiviral Activity

“…Rev functions by oligomerizing on the RRE of viral RNA molecules through interactions between Rev monomers (29). Given the essential role of Rev in HIV-1 replication it is a potentially viable, but as yet largely untested, target for antiviral intervention (9,30).…”